Zone 2 Heart Rate Calculator
Zone 2 heart rate is 60–70% of your maximum heart rate, or 60–70% of your heart-rate reserve plus your resting heart rate when using the Karvonen formula.
verified_userReviewed by the Calculopedia editorial teamLast updated 2026-08-16
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quizExample
How this calculator works, with real numbers (no JavaScript needed):
Inputs
- Age
- 35
- Method
- maxHr
- Resting heart rate
- 60
Results
- Zone 2 — lower bound
- 111
- Zone 2 — upper bound
- 130
- Maximum heart rate
- 185
- Method used
- Percentage of max HR (60–70%)
functionsThe formula
Zone 2 is the aerobic "fat-burn" zone — easy enough that you can hold a conversation, intense enough to build your aerobic base. It is the foundation of endurance training, and it has surged in popularity among runners, cyclists and gym-goers for good reason: it is where much of your cardiovascular engine gets built.
The percentage method
Max HR is estimated as 220 − age. Zone 2 sits at 60–70% of max HR:
Zone 2 = 0.6 × max HR to 0.7 × max HR
For a 35-year-old: max HR = 185, so Zone 2 = 111–130 bpm.
The heart-rate reserve and Karvonen
Karvonen uses your heart-rate reserve (HRR = max HR − resting HR), which accounts for how fit you already are:
Lower = 0.6 × HRR + resting HR
Upper = 0.7 × HRR + resting HR
Same 35-year-old with a 60 bpm resting HR: HRR = 125 → Zone 2 = 135–147 bpm. A lower resting HR (fitter heart) raises your Zone 2 numbers — which is why Karvonen is more accurate for athletes.
Where Karvonen comes from
The method is named after the Finnish physiologist Martti Karvonen, who worked on the concept of heart-rate reserve in the 1950s. His key insight was that the range between your resting and maximum heart rate is what training moves, not raw max HR alone. By anchoring zones to your personal reserve instead of a fixed percentage of max, Karvonen's approach personalises the range for your current fitness level — the exact reason two people of the same age can train at quite different heart rates yet work equally hard.
Why train in Zone 2 (and why it is not "fat burn" magic)
- Burns fat as a primary fuel.
- Builds capillary density and mitochondria — your endurance engine.
- Allows high weekly volume without excessive fatigue.
A word on the "fat-burn" label: your body always uses a mix of fat and carbohydrate for fuel, and the proportion of fat is higher at easy intensities. That does not mean low-intensity exercise melts fat more efficiently overall — total calories matter more. What Zone 2 genuinely delivers is the aerobic infrastructure that lets you sustain higher work over time, which is a different and more important benefit than the marketing phrase suggests.
If you cannot hold a conversation at your Zone 2 pace, drop the intensity. Zone 2 is meant to feel easy — that is the point.
helpFrequently asked questions
question_markHow do I calculate my Zone 2 heart rate?
Estimate max HR as 220 − age, then take 60–70% of it. For a 35-year-old: 185 × 0.6 to 185 × 0.7 = 111–130 bpm. The Karvonen method gives a more personal range using your resting HR.
question_markWhat is Zone 2 heart rate used for?
Zone 2 is the aerobic base-building zone. Training there improves fat burning and endurance while staying easy enough to recover from day to day.
question_markKarvonen or percentage of max HR — which is better?
Karvonen is more accurate for fit individuals because it accounts for resting heart rate. The simple percentage method is fine for general fitness and easy to calculate.